Barcode verification is the most certain way to assure that you are printing good codes

About barcode verification and standards.

The Importance of Verification

The ease with which a bar code can be read depends upon how well the code has been printed, and on certain parameters of the scanner. Specifications lay down the ideal dimensions and methods of production of codes, but it is not always possible to adhere to the ideal conditions. Therefore, in practice, bar codes can be produced that are not perfect and which may or may not scan successfully. In addition there are other problems that can occur in the printing or production process which may contribute to the difficulty of scanning.

So how can the chances of a code scanning be assessed?

Traditionally there have been a few ways of trying to ensure that a code will scan. The retail barcode system, which is organised world wide by the EAN organisation, has relied on accurate film masters to be used in the creation of printing plates to attain the quality required. However, not all codes are printed on large presses, and these other printing processes have various limitations and potential error conditions.

Verification equipment has been around for some years to assess the dimensional accuracy of printed codes. Although these devices have proved extremely useful, their results may not fully explain why a code will or will not read.

New Verification Standards

In order to create a universal international standard for verification equipment that assesses the printed bar code from the point of view of scanning and decoding rather than the dimensional accuracy of the ink on the paper, the American National Standards Institute (ANSI) has developed a new method of analysing the printed code.

This method, which has already been adopted in the European Community (CEN) and is now a world standard (ISO), is far more detailed than the previous methods of verification, but it does reveal more possible problems with a printed bar code. In particular it highlights problems that are associated with printers used for generating bar-coded labels, where printer machinery faults may cause unwanted gaps, holes or specks of ink in places where smooth coverage of ink or absence of ink should exist. It also highlights the problems that can occur when mixtures of colours are used, such as on magazine covers.

Verifiers use the ANSI/CEN/ISO grading system which takes into account seven main parameters:

• Minimum Reflectance
• Symbol Contrast
• Minimum Edge Contrast
• Modulation
• Defects
• Decodability
• Decode

For each scan the lowest single grade of these seven (being the weakest link in the chain) becomes the overall grade. After the recommended ten scans have been taken, the results are averaged, and each parameter, including the overall grade, is graded A-F (ANSI) or 4-0 (CEN/ISO).

The required pass grade for most major retailers is a grade 2 (C) or above for all bar codes, with the exception of those printed directly onto corrugated fibreboard, for which a Grade 1 (D) is normally acceptable. However, you should check with your customers for their specific grade requirements.

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Why should you verify your barcodes

Bar code verification is the most certain way to assure that you are printing good codes. The bar code, which began circa 1975, is virtually everywhere. You cannot find a product that does not have a bar code associated with it somewhere in its life. It is probably the least expensive and most reliable method of entering data.

The bar code has gone through three distinct phases. Phase one was 1975 to 1990. During this phase the codes were printed but not widely used. Bad bar codes did not matter at this time. However, it was a necessary phase, the bar codes needed to be out there before users could justify spending money on equipment to read them. Phase two was approximately 1990 to 1998. During this phase bar codes were a productivity enhancement tool. A bad code caused productivity degradation. If a code did not scan there was a back up system in place, a person. Grocery stores are an example of an industry in phase two. If the code does not scan, the cashier simply manually inputs the data. Problems that occur in phase two are productivity bottlenecks, potential human error, potential over use injuries and the requirement for a higher level of training. Phase three is now. Bar codes are enterprise critical. Highly automated systems require barcodes that are readable; readable every time. These systems have no manual back up data entry system. We see examples of phase three industries in automated material handling, medical and large retail store chains just to name a few.

So, how do you get to phase three? It is simple, print perfect bar codes or check the bar codes immediately after or during the printing process.

Despite what a printer manufacturer may say, there is no perfect print process. Thermal printers may have ribbon wrinkles, burned out print head elements, improper heat and speed settings or a miss-marriage of the ribbon and face stock. Impact printers may have miss-aligned hammers or an over used ribbon. Laser printers may have fuser problems, low toner or a face stock that is improperly top coated. Lastly, ink jet systems contend with clogged jets, low contrast and differing substrates. With that being said, printers today do produce high quality print and any printer type, if properly maintained, will print good bar codes, most of the time. However, this may even make the problem worse. Knowing that the printer is likely to print a good code means that inspection becomes less appealing. Companies cannot afford to have someone do constant visual inspection and if they could the inspector would rapidly lose interest. This means that bar codes go unchecked. Enter the need for verification.

A verifier is not the same as a scanner. A scanner is typically a mass-produced item that provides machine recognition of the data encoded in a bar code symbol. Using a barcode scanner to read a bar code only assures that the scanned bar code has some region on it that is readable, by that scanner. Therefore, the better the scanner, the less bar code quality assurance is maintained. A verifier, on the other hand, is a precision instrument that is made to predict how well the bar code will be read by the typical scanner, any scanner. It should decode, measure and check formatting of even the most inferior symbol and indicate area(s) that are deficient so that corrective action may take place.

There are two methods of bar code verification, traditional and ANSI. Traditional verification analyzes how well the code was printed. It looks at parameters such as print contrast, absolute element widths and average bar deviation. ANSI verification predicts how well a scanner incorporating a particular wavelength of light and a particular aperture size will read a symbol. ANSI looks at eight criteria: edge determination, minimum reflectance, minimum edge contrast, symbol contrast, modulation, defects, decodability and decode. It does this by taking a scan reflectance profile of the code and analyzing that profile.

Where should a verification system be placed? Verification should take place right after or during the printing process and before the bar codes enter the system. If you are printing bar codes for others to scan, you should verify with the philosophy that any bad bar codes should be reprinted. If you are receiving bar codes from others, you should verify before letting bar codes into your system.

Why should verification systems be put into place? Verification should be done to ensure that the bridge between printing and scanning is accurate, to minimize faulty scanning and to ensure that inferior codes do not enter the system. Inferior codes cost time, productivity and money. If a code does not read at all there is a return to the slow, error prone manual data entry and this causes bottlenecks or may stop enterprise critical applications. If the code reads after several attempts there is a waste of time and a chance of repetitive movement injuries. And, if a code reads with errors then there is a contamination of your database.

What industries need verification? Every industry that has a high cost associated with printing bad bar codes should have a verification system in place. Let’s face it, if the cost of printing a bad bar code is non-existent or minimal there is no need to check the code. However, the converse is also true. If by printing a bad bar code you receive fines, potentially lose business, have to do costly re-work or have other potential high cost repercussions then a verification system is warranted. Many industries need verification systems. Suppliers to major retail chains need to avoid getting fined for non-readable bar codes. People printing bar codes directly onto corrugated materials need to ensure readability of the code against low contrast. Printing companies providing bar codes printed on press and imprint houses providing bar codes printed on printers can avoid costly re-work of jobs by implementing a verification system. Medical and pharmaceutical suppliers need to ensure properly marked product to avoid dispensation of incorrect materials. Chemical companies need to ensure properly marked product to avoid costly fines and law suits. Suppliers to the automotive industry need to ensure labels meet the AIAG specification. Suppliers to the USPS should check the quality of their linear codes to meet the Postal specifications. Anyone running a highly automated warehouse that uses scanners to route packages can avoid bottlenecks and stops by putting a verification system in place. Many industries should have verification systems due to substantial repercussions for printing bad codes.

One last thought, if you are spending thousands of dollars on an AIDC system with labeling, data collection, inventory control or the like, shouldn’t you ensure that the bar codes for that system are able to be read?

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